Thermoplastic polymer composition

ABSTRACT

A thermoplastic polymer composition comprises: 
     a thermoplastic polymer (a) having polarity on the main chain of the molecule thereof, and 
     a modified block copolymer (b) of a block copolymer comprising: 
     at least one polybutadiene block (B) having a degree of vinylization of not more than 30%, and 
     at least one polymer block (D) comprising units from isoprene and butadiene in a ratio by weight of isoprene/butadiene of 30/70 to 100/0 and having a degree of vinylization of not more than 30%, 
     said polybutadiene block (B) and said polymer block (D) each has a degree of unsaturation of not more than 30%, to said block copolymer a molecular unit containing a carboxyl acid group or derivatives thereof having added, the ratio by weight between said component (a) and said component (b), (a)/(b), being in a range of 2/98 to 98/2.

This is a Division of application Ser. No. 08/230,837 filed on Apr. 21,1994, now U.S. Pat. No. 5,446,092.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermoplastic polymer compositionand, more specifically, to a thermoplastic polymer compositioncomprising a thermoplastic polymer having polarity on the main chainthereof and a modified block copolymer to which a carboxylic acid groupor derivatives thereof has added, the composition having excellentmechanical characteristics with the two components having improvedcompatibility.

2. Description of the Related Art

Polymeric substances have been widely used as materials for fibers,films, sheets and like shaped articles, and it sometimes happens thatthese substances, when used alone, do not sufficiently meet the intendedpurpose. A variety of attempts have therefore been made to combine apolymeric substance with other components to form compositions orlaminates, thereby providing the resulting products with sufficientstrength, improved processability, reduced cost or like advantages.However, different types of polymeric substances, when combined togetherto form a composition, seldom have good compatibility with each other.As a result, most of compositions comprising different types ofpolymeric substances with poor compatibility have problems in achievingthe intended improvements due to non-uniformity, inter-layerdelamination between the different polymer layers or like troublesresulting from the poor compatibility.

It is known, in order to obtain compositions having good properties byblending different polymeric substances, to use as one component a blockcopolymer comprising a polystyrene block and a polybutadiene block, onecomprising a polystyrene block and a polyisoprene block, or ahydrogenated block copolymer obtained by partially hydrogenating theforegoing (for example, Japanese Patent Application Laid-open Nos.119055/1975, 148457/1975, 75651/1975, 117940/1977 and 150457/1977).However, these block copolymers cannot be said to be useful forimproving the characteristics of thermoplastic polymers having polarityon their main chain, such as polyamides, thermoplastic polyesters andthermoplastic polyurethanes, because of markedly poor compatibility withthese polymers.

There are known compositions capable of modifying polyamides,thermoplastic polyesters, thermoplastic polyurethanes and the like,incorporating into these thermoplastic polymers a block copolymerobtained by permitting a carboxylic acid or derivatives thereof to addto a partially hydrogenated product of a block copolymer comprising anaromatic vinyl compound polymer block and a conjugated diene compoundpolymer block (for example, U.S. Pat. Nos. 4,174,358, 4,628,072,4,659,970, 4,820,768 and 4,972,020). However, although thesecompositions, with an improved compatibility of the thermoplasticpolymers with themselves, exhibit relatively better mechanicalproperties, they have poor resistance to shock at low temperatures andhave some problem with respect to oil resistance.

There are compositions incorporating a thermoplastic polymer such aspolyamides, polyethylene terephthalate or polybutylene terephthalate anda block copolymer obtained by permitting a carboxylic acid orderivatives thereof to add to a partially hydrogenated product of ablock copolymer having a structure of X--Y--X or X--Y--X--Y, wherein Xand Y represent a polybutadiene block having a degree of vinylization ofnot more than 20% and one having a degree of vinylization of 30 to 95%,respectively (Japanese Patent Application Laid-open No. 74409/1991). Thecompositions still have the drawback of poor impact strength at lowtemperatures, while eliminating the problem of poor oil resistancethough.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide athermoplastic polymer composition having excellent mechanicalproperties, in particular impact strength, more specifically that at lowtemperatures, as well as excellent oil resistance, by improving thecompatibility of the thermoplastic polymer and a hydrogenated blockcopolymer with each other.

The present inventors have found that a block copolymer having aspecific structure is effective in achieving the object, to complete theinvention.

Thus, the present invention provides a thermoplastic polymer compositioncomprising:

a thermoplastic polymer (a) having polarity on the main chain of themolecule thereof, and

a modified block copolymer (b) of a block copolymer comprising:

at least one polybutadiene block (B) having a degree of vinylization ofnot more than 30%, and

at least one polymer block (D) comprising units from isoprene andbutadiene in a ratio by weight of isoprene/butadiene of 30/70 to 100/0and having a degree of vinylization of not more than 30%,

said polybutadiene block (B) and said polymer block (D) each has adegree of unsaturation of not more than 30%, to said block copolymer amolecular unit containing a carboxyl acid group or derivatives thereofhaving added, the ratio by weight between said component (a) and saidcomponent (b), (a)/(b), being in a range of 2/98 to 98/2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The modified block copolymer used as component (b) in the presentinvention is produced for example as follows. There is hydrogenated ablock copolymer comprising at least one polybutadiene block (B) having adegree of vinylization of not more than 30%, and at least one polymerblock (D) comprising units from isoprene and butadiene in a ratio byweight of isoprene/butadiene of 30/70 to 100/0 and having a degree ofvinylization of not more than 30%. A carboxylic acid or derivativesthereof is then permitted to add to the obtained hydrogenated product,to obtain the modified block copolymer.

The above block copolymer before being hydrogenated contains at leastone, preferably at least 2 polybutadiene block (B) and at least onepolymer block (D).

In the block copolymer before being hydrogenated, where polymer block(D) contains a butadiene component in addition to an isoprene component,the polymer block is obtained by polymerizing a mixture of isoprene andbutadiene.

In the block copolymer, the ratio by weight between polybutadiene block(B) and polymer block (D) is preferably in a range of 10/90 to 90/10,more preferably in a range of 20/80 to 85/15.

The polybutadiene block (B) has a degree of vinylization of not morethan 30%, preferably not more than 20%. If the polybutadiene block (B)has an degree of vinylization exceeding 30%, the block will have poorcrystallinity, thereby decreasing the oil resistance of the resultingcomposition.

It is necessary that the polymer block (D) contain isoprene units in anamount of at least 30% by weight. If the content of isoprene units isless than 30% by weight, the block will have poor low temperaturecharacteristics. It is also necessary that the polymer block (D) have adegree of vinylization of not more than 30%. If the degree ofvinylization of polymer block (D) is less than 30%, the block will havea high glass transition point, thereby becoming inferior in lowtemperature characteristics.

It is desirable that the above block copolymer have a number averagemolecular weight in a range of 20,000 to 500,000 and a molecular weightdistribution in terms of a ratio between the weight average molecularweight and the number average molecular weight of 1.05 to 10. The blockcopolymer may have any structure, such as linear, branched, radial, orcombinations of the foregoing.

Representative examples of structures possessed by the block copolymerare (B-I)n, (B-I)n-B, [B-(I/B)]n,[B-(I/B)]n-B (n: an integer of 1 to 5),(B-I)-X and [B-(I/B)]-X (X: 3- to 10-multifunctional coupling agentresidue), wherein B, I and (I/B) represent, respectively, apolybutadiene block having a degree of vinylization of not more than30%, an isoprene block having a degree of vinylization of not more than30% and a polymer block obtained by polymerizing a mixture of isopreneand butadiene in such a manner that the resulting degree of vinylizationbecomes not more than 30%.

Where the block copolymer contains at least 2 polybutadiene blocks (B),these blocks may either have the same structure or be different in themolecular weight, molecular weight distribution, microstructure or likestructures. Likewise, when the block copolymer contains at least 2polymer blocks (D), these blocks may either have the same structure orbe different in the mixing ratio of isoprene/butadiene, molecularweight, molecular weight distribution, microstructure or likestructures.

The above block copolyer is generally obtained by subjecting monomersincluding butadiene and isoprene to successive anionic polymerization ina solvent of inactive hydrocarbon solvent such as benzene, toluene,hexane or cyclohexane and with a catalyst of an organolithium compoundsuch as lithium butyl. It is also possible to react the block copolymerhaving a lithium-active terminal obtained during the above process witha multi-functional coupling agent such as carbon tetrachloride orsilicon tetrachloride, to obtain a branched or radial-type blockcopolymer. In the present invention, those block copolymers that areobtained by other polymerization processes, such as radicalpolymerization and stereo-regulating polymerization can also be used, aslong as they satisfy the above requirements.

The block copolymer is hydrogenated by a known process, such as onedescribed in Japanese Patent Publication No. 8704/1967. It is necessarythat, in the block copolymer, both polybutadiene block (B) and polymerblock (D) have a degree of unsaturation of not more than 30%, in view ofweather resistance and heat resistance.

The degree of unsaturation of a polymer block herein means the contentof carbon-carbon double bonds in the polymer block and is determined byinstrumental analysis such as nuclear magnetic resonance (NMR) analysisor infrared absorption (IR) spectrometry or chemical analysis such asiodometry.

The hydrogenated block copolymer obtained is then modified by additionof a carboxylic acid or its derivatives. Examples of usable carboxylicacids or their derivatives are maleic acid, maleic anhydride, fumaricacid, itaconic acid, acrylic acid, methacrylic acid, methylmethacrylate, glycidyl methacrylate, crotonic acid,cis-4-cyclohexene-1,2-dicarboxylic acid or its anhydride,endo-cis-bicyclo[2,2,1]-5-heptene-2,3-dicarboxylic acid or its anhydrideand maleinimide. Among these compounds, maleic anhydride and glycidylmethacrylate are particularly preferred. These unsaturated carboylicacids may be used singly or in combination of 2 or more.

The addition of a carboxylic acid or its derivatives to the hydrogenatedblock copolymer can be conducted in a solution or bulk and in thepresence or absence of a radical initiator. A preferred processcomprises reacting the hydrogenated block copolymer and a carboxylicacid or its derivatives in, for example, an extruder and in the presenceof a radical initiator.

There are no specific restrictions with respect to the process forproducing the modified block copolymer, but it is not recommended toselect such a process as to permit the resulting modified blockcopolymer to contain undesirable components such as gels in amountsexceeding designated levels or to have a markedly high melt viscosity,which impairs processability. A carboxylic acid may be introduced intoone end or both ends of the modified block copolymer by blowing carbondioxide after completion of the anionic polymerization.

The amount of addition of a carboxylic acid or its derivatives to thehydrogenated block copolymer is preferably 0.01 to 20 parts by weightbased on 100 parts by weight of the hydrogenated copolymer, morepreferably 0.1 to 10 parts by weight on the same basis. If the additionamount is less than 0.01 part by weight, the obtained modified blockcopolymer will produce very little effect of improvement by themodification as compared with the block copolymer before modification.On the other hand, the improvement effect hardly further increases withthe addition exceeding 20 parts by weight.

The thermoplastic polymer having polarity in the main chain,constituting another component in the composition of the presentinvention, is now described.

The thermoplastic polymer having polarity in the main chain as referredto in the present invention includes those that can chemically bond to,or induce a strong interaction with, the carboxylic acid or itsderivatives having added to the hydrogenated block copolymer. Example ofthese polymers are thermoplastic polymers containing amido-bonds,ester-bonds or urethane-bonds. Thus, the thermoplastic polymers havingpolarity in the chain include polyamides, thermo-plastic polyesters andthermoplastic polyurethanes, the terminals or side chains of which maybe bonded to other functional groups.

Polyamides usable in the present invention are polycondensates of adicarboxylic acid and a diamine, polycondensates of an α-aminocarboxylicacid, products of ring-opening polymerization of a cyclic lactam and thelike, and their concrete examples are nylon-6, nylon-66, nylon-610,nylon-11 and nylon-12, and copolymers of the foregoing, such asnylon-6-nylon-66 copolymer, nylon-6-nylon-12 copolymer and semi-aromaticpolyamides as represented by the following structural formula; ##STR1##wherein n represents an integer of 2 to 12.

It is desirable that these polyamides have a number average molecularweight and a melting point of 200 to 30,000 and 150° to 270° C.respectively, and more preferably not more than 20,000 and 260° C.,respectively, within these ranges, to obtain compositions havingexcellent processability.

These polyamides may be used singly or in combination of 2 or more.

Polyesters usable in the present invention should be thermoplastic.Polyesters contain in the molecules thereof ester-bonds andrepresentative polyesters have a structure of polycondensates of adicarboxylic acid and a glycol (or diol). These polyesters are obtainedby polycondensation of a dicarboxylic acid, lower alkyl esters thereof,acid hydrides thereof or acid anhydrides thereof, with a glycol.Examples of aromatic or aliphatic dicarboxylic acids usable for thispurpose are oxalic acid, malonic acid, succinic acid, glutaric acid,pimelic acid, suberic acid, adipic acid, sebacic acid, azelaic acid,1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid,1,16-hexadecanedicarboxylic acid, terephthalic acid, isophthalic acid,p,p'-dicarboxydiphenyl, p-carboxyphenoxyacetic acid and2,6-naphthalenedicarboxylic acid. These dicarboxylic acids can also beused in optional combinations. Among these, terephthalic acid andisophthalic acid are particularly preferred.

Glycols (or diols) usable as another starting material for the abovepolyesters includes aliphatic and aromatic ones and their examples areethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol,1,6-hexanediol, 1,4-cyclohexanediol, 1,9-nonanediol, 1,10-decanediol,neopentyl glycol and p-xylene glycol. These glicols may be used singlyor in any optional combination. Among these, ethylene glycol,1,4-butanediol and 1,9-nonanediol are particularly preferred. Amongpolyesters comprising dicarboxylic acid units and glycol units,polyethylene terephthalate and polybutylene terephthalate are useful,part of monomer units of which may be replaced by other monomer units.

These polyesters preferably has a molecular weight of 500 to 100,000,more preferably 5,000 to 50,000.

These polyesters may be obtained by any polymerization process with nospecific restrictions. Thus, the above acid component, e.g. terephthalicacid, isophthalic acid, an aliphatic dicarboxylic acid, or ester-formingderivatives of the foregoing can, together with one of the glycols, atthe same time or successively, be subjected to direct esterification ortransesterification, followed by polymerization. On this occasion, aconventional, optional catalyst, stabilizer, modifying agent and otheradditives may be used.

As other useful polyesters, polylactones obtained by ring-openingpolymerization of a cyclic lactone, such as pivalolactone,β-propiolactone or ε-caprolactone.

These polyesters have hydroxyl groups or carboxylic groups at themolecular terminals thereof, which may further be reacted with amonofunctional alcohol or carboxylic acid for deactivation. Thepolyester used in the present invention preferably has at part or all ofits molecular terminals functional groups capable of reacting with thefunctional group of the modified block copolymer used. Use of apolyester having this type functional groups markedly improves thecompatibility of the resulting composition by undergoing reaction,partially, with the modified block copolymer.

The above polyesters can be used either singly or in combination of 2 ormore.

The thermoplastic polyesters useful in the present invention include,not only those used for preparing fibers, films and resins, such aspolyethylene terephthalate, but also polybutylene terephthalate andpolyethylene naphthalate and those having a lower melting point andlower crystallinity than the foregoing, as well as polyetherester blockpolymers having hard segments and soft segments in one and the samemolecule.

Thermoplastic polyurethanes usable in the present invention areclassified, according to their synthesis conditions, into completelythermoplastic type and incompletely thermoplastic type, which aredetermined by the molar ratio between the OH groups in the startingmaterial di-functional polyol or glycol and the NCO groups in theisocyanate. That is, those having been synthesized under the conditionsof about 0.95<NCO/OH≦1.1 belong to completely thermoplastic type, whilethose under about 1.1<NCO/OH to incompletely thermoplastic type. Thesethermoplastic polyurethanes include ones having soft segments of apolyol (polyester or polyether) and a diisocyanate and hard segments ofa diisocyanate and a glycol.

Examples of usable starting material polyester diols arepoly(1,4-butylene adipate), poly(1,6-hexane adipate andpolycaprolactone, and examples of usable starting material polyetherdiols are polyethylene glycol, polypropylene glycol andpolyoxytetramethylene glycol. Examples of glycols are ethylene glycol,1,4-butanediol and 1,6-hexanediol. Usable glycols include aromatic,alicyclic and aliphatic ones and their examples are tolylenediisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylenediisocyanate and isophorone diisocyanate.

Besides the above thermoplastic polyurethanes, polyurethanes used foradhesives, foams, paints and the like are also usable in the presentinvention, as long as they have sufficient compatibility with themodified block copolymer, which is component (b) in the presentinvention.

These thermoplastic polyurethanes preferably have a molecular weight of5,000 to 500,000, more preferably 10,000 to 300,000, in view ofmechanical properties.

The features of the thermoplastic polymer composition of the presentinvention is described next.

The compositions of the present invention, utilizing as their componenta hydrogenated block copolymer modified by a carboxylic acid or itsderivatives, has the feature of having markedly improved compatibilitywith polar thermoplastic polymers, as compared with hydrogenated blockcopolymers unmodified.

That is, while compositions comprising an unmodified hydrogeneated blockcopolymer and a polar thermoplastic polymer, the two components havingpoor compatibility, have poor dispersibility and become opaque when thetwo components have different refractivities, the compositions of thepresent invention comprising a modified hydrogenated block copolymer anda polar thermoplastic polymer have good dispersibility and improvedtransparency, as well as good mechanical properties.

The compositions of the presen invention can exhibit a variety ofmechanical properties according to the ratio between the modifiedhydrogenated block copolymer and polar thermoplastic polymer used, fromrubber- or leather-like to solid resin-like. With a prevailing contentof the modified hydrogenated copolymer, there is obtained a rubber- orleather-like composition having higher hardness and tensile strength andbetter resistance to oil and heat than those of conventionalcompositions comprising polystyrene block and polybutadiene block orcompositions comprising polystyrene block and polyolefin block. As thecontent of the thermoplastic polymer increases, the resultingcompositions become of tougher nature like solid resins and exhibitmarked effect of improving shock resistance, adhesiveness and resistanceto folding, the degree of improvement varying according to the type ofthe polar thermoplastic polymer used though.

The modified block copolymers used in the present invention, its degreeof unsaturation being specified as not exceeding 30%, exhibit excellentresistance to weather and heat.

In the compositions of the present invention, the thermoplastic polymer(a) and the modified block copolymer (b) is used in a ratio by weight of(a)/(b) of 2/98 to 98/2, preferably 5/95 to 95/5. Too small a content ofcomponent (a) produces little effect as a rubber-like composition, whiletoo large a content of (a) produces little effect as a solid resin.

In particular, compositions obtained by using a polar thermoplasticpolymer (a) and a modified block copolymer (b) in a ratio by weight of(a)/(b) of 2-50/98-50 are useful as those having improved the modifiedblock copolymer, and compositions with an (a)/(b) of 98-50/2-50 areuseful as those having improved the properties, in particular shockresistance, of the polar thermoplastic polymer.

The compositions of the present invention may contain as part of theircomponents a graft copolymer comprising the modified block copolymer andpolar thermoplastic polymer and formed by reaction of reactive groupscontained in the modified block copolymer and those contained in thepolar thermoplastic polymer used.

The modified block copolymers used in the present invention can besuitably used as agents for improving the compatibility of thermoplasticpolymer having polarity in the main chain with polyolefin-basedthermoplastic polymers such as polypropylene and polyethylene.

The compositions of the present invention can be prepared, according tothe ratio of the contents of their components, with conventionalapparatuses for mixing the usual polymers.

For example, the mixing is conducted through an extruder, mixing roll,Banbary mixer or kneader, and melt blending through an extruder isparticularly preferred in the present invention.

The thermoplastic polymer compositions of the present invention canincorporate, within amounts not to impair the properties, reinforcingagents and/or fillers, e.g. calcium carbonate, silica, carbon black,glass fibers and clay, as well as plasticizers, e.g. polyethylene glycoland phthalic acid esters. Further other additives, e.g. a heatstabilizer, antioxidant, UV-absorber, colorant, pigment and releasingagent can be added, and it is also possible to add a foaming agent tothe compositions of the present invention to make them foamed bodies.

The thermoplastic polymer compositions of the present invention can bemolded by any one of known process, e.g. extrusion molding, injectionmolding, tubular film process, compression molding, vacuum molding andcalendering, into sheets, films or other various shaped articles. Thepolymer compositions can also be formed into nonwovens or like fibrousarticles by melt blowing, spunbonding process or like methods. Examplesof concrete items of these finished goods are interior and exteriorparts of automobiles, such as bamper and inside panels; housing ofhousehold-use electric appliances such as TV, stereophonic gramophonesand vacuum cleaner; electrical and electronic parts such as connector;materials for electric cables; food packaging materials and foodcontainers, such as trays for meat and fresh fish and packing materialsfor fruits and vegetables; packing materials for industrial goods;sports goods, such as sport shoes; clothing and leather products;daily-use sundries, such as toys and sandals; various films, sheets andlaminates; adhesives and tacky adhesives; elastic materials used fordisposable diapers and the like; various rubber products, such as hoses,tubes and belts and medical care products. The polymer compositions arethus useful for a markedly wide range of end-uses.

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLES Reference Example

[Preparation of modified hydrogenated block copolymers]

1. Polymerization for block copolymers and hydrogenation thereof

1-(1)

A tri-block copolymer having a structure of butadiene-isoprene-butadienewas obtained, in a solvent of cyclohexane and with a polymerizationcatalyst of lithium n-butyl, by feeding successively butadiene, isopreneand finally butadiene.

The block copolymer obtained was hydrogenated with a mixed catalyst ofcobalt naphthenate and aluminum triethyl under a hydrogen pressure of 10kg/cm², into a hydrogenated block copolymer having a hydrogenation ratioof 95%. This polymer was named R-1.

1-(2)

A hydrogenated butadiene-isoprene di-block copolymer having ahydrogenation ratio of 96% was obtained in the same manner as in 1-(1).This polymer was named R-2.

1-(3)

A hydrogenated butadiene-isoprene/butadiene mixture-butadine tri-blockcopolymer having a hydrogenation ratio of 96% was obtained in the samemanner as in 1-(1). This polymer was named R-3.

1-(4)

A hydrogenated styrene-isoprene-styrene tri-block copolymer having ahydrogenation ratio of 96% was obtained in the same manner as in 1-(1).This polymer was named R-4.

1-(5)

Butadiene was polymerized in a cyclohexane solvent with a polymerizationcatalyst of lithium n-butyl. Then, tetrahydrofuran was added as avinylization agent, to polymerize butadiene, to obtain a butadiene-vinylbutadiene copolymer. The copolymer had a degree of vinylization of vinylbutadiene part of 60%. The polymer was hydrogenated to give ahydrogenated block copolymer having a hydrogenation ratio of 98%. Thispolymer was named R-5.

Table 1 shows the properties of these 5 copolymers.

                                      TABLE 1                                     __________________________________________________________________________                           Amount of    Amount of                                           Number                                                                              Content of                                                                           1,2-bonds in                                                                         Content                                                                             1,2-bonds in   Mixing ratio                         average                                                                             1,4-butadiene                                                                        1,4-butadiene                                                                        of styrene                                                                          1,2-butadiene                                                                        Degree of                                                                             of isoprene/                         molecular                                                                           block  block  block block  hydrogenation                                                                         butadiene                  Type                                                                             Structure                                                                            weight                                                                              (wt %) (mole %)                                                                             (wt %)                                                                              (mole %)                                                                             (%)     (wt %)                     __________________________________________________________________________    R-1                                                                              B--I--B                                                                              45,000                                                                              30     7      --    --     95      --                         R-2                                                                              B--I   78,000                                                                              20     7      --    --     96      --                         R-3                                                                              B--(I/B)--B                                                                          128,000                                                                             30     7      --    --     96      60/40                      R-4                                                                              S--I--S                                                                              45,000                                                                              --     --     30    --     96      --                         R-5                                                                              B--VB  70,000                                                                              30     7      --    60     98      --                         __________________________________________________________________________

2. Modification of hydrogenated block copolymers

2-(1) Modification with maleic anhydride (MAH)

To 100 parts by weight of the hydrogenated block copolymer (R-1)obtained in 1-(1), there were added 2 parts by weight of maleicanhydride and 0.2 part by weight of a dialkyl peroxide (PERHEXA 258,made by Nippon Oil & Fats Co., Ltd.) and the obtained mixture was fed toa twin-screw extruder (screw diameter: 35 mm, L/D=30) under anatmosphere of nitrogen and reacted at a cylinder temperature of 230° C.,while unreacted maleic anhydride was being removed by vent-suction.

The modified hydrogenated block copolymer had a maleic anhydrideaddition content of 1.7% by weight/polymer.

2-(2) Modification with glycidyl methacrylate (GMA)

To 100 parts by weight of the hydrogenated block copolymer (R-2)obtained in 1-(2), there were added 1 part by weight of glycidylmethacrylate and 0.15 part by weight of PERHEXA 258 (made by Nippon Oil& Fats Co., Ltd.) and the obtained mixture was subjected to modificationreaction in the same manner as in 2-(1).

The modified hydrogenated block copolymer had a GMA addition content of0.6% by weight/polymer.

2-(3) Modification with maleic anhydride (MAH)

To 100 parts by weight of the hydrogenated block copolymer (R-3)obtained in 1-(3), there were added 3 parts by weight of maleicanhydride and 0.3 part by weight of PERHEXA 25B (made by Nippon Oil &Fats Co., Ltd.) and the obtained mixture was subjected to modificationreaction in the same manner as in 2-(1).

The modified hydrogenated block copolymer had a maleic anhydrideaddition content of 2.5% by weight/polymer.

2-(4) Modification with maleic anhydride (MAH)

To 100 parts by weight of the styrene-based hydrogenated block copolymer(R-4) obtained in 1-(3), there were added 3 parts by weight of maleicanhydride and 0.3 part by weight of PERHEXA 258 (made by Nippon Oil &Fats Co., Ltd.) and the obtained mixture was subjected to modificationreaction in the same manner as in 2-(1).

The modified hydrogenated block copolymer had a maleic anhydrideaddition content of 2.3% by weight/polymer.

2-(5) Modification with glycidyl methacrylate (GMA)

To 100 parts by weight of the styrene-based hydrogenated block copolymer(R-4) obtained in 1-(4), there were added 1.5 parts by weight ofglycidyl methacrylate (GMA) and 0.2 part by weight of PERHEXA 258 (madeby Nippon Oil & Fats Co., Ltd.) and the obtained mixture was subjectedto modification reaction in the same manner as in 2-(1).

The modified hydrogenated block copolymer had a GMA addition content of0.7% by weight/polymer.

2-(6) Modification with maleic anhydride (MAH)

To 100 parts by weight of the hydrogenated butadiene-vinyl butadieneblock copolymer (R-5) obtained in 1-(5), there were added 3 parts byweight of maleic anhydride and 0.3 part by weight of PERHEXA 25B (madeby Nippon Oil & Fats Co., Ltd.) and the obtained mixture was subjectedto modification reaction in the same manner as in 2-(1).

The modified hydrogenated block copolymer had a maleic anhydrideaddition content of 2.6% by weight/polymer.

The modified hydrogenated block copolymers obtained in the above 2-(1)through (6) were named M-1, G-2, M-3, M-4, G-4 and M-5, respectively.Table 2 shows the amounts of modification of these copolymers.

                  TABLE 2                                                         ______________________________________                                                             Amount of  Amount of                                             Block        modification                                                                             modification                                          copolymer    with MAH   with GMA                                      Name    used         (wt %)     (wt %)                                        ______________________________________                                        M-1     R-1          1.7        --                                            G-2     R-2          --         0.6                                           M-3     R-3          2.5        --                                            M-4     R-4          2.3        --                                            G-4     R-4          --         0.7                                           M-5     R-5          2.6        --                                            ______________________________________                                         MAH: maleic anhydride;                                                        GMA: glycidyl methacrylate.                                              

Example 1 and Comparative Examples 1 through 4

There were pre-mixed 80 parts by weight of a sufficiently dried nylon-66(PA66) (AMIRAN CM3001N, made by Toray Industries, Inc.) and 20 parts byweight of the modified hydrogenated block copolymer (M-1), modifiedstyrene-based hydrogenated block copolymer (M-4) or unmodifiedhydrogenated block copolymer (R-1). The obtained mixtures were each meltblended through a twin-screw extruder under an atmosphere of nitrogenand at a temperature of 270° C.

The pellets of compositions obtained were injection molded into testspecimens. The specimens were tested for bending modulus, notched Izodimpact strengths at 25° C. and -25° C. and weight reduction byextraction with toluene. The results are shown in Table 3. It isapparent from Table 3 that composition using the modified hydrogenatedblock copolymer (M-1) had better stiffness, oil resistance and shockresistance compared with Comparative Examples 1 through 4, thus provingthe marked improvement achieved by addition of the modified hydrogenatedblock copolymer.

Example 2 and Comparative Examples 5 through 7

There were premixed 80 parts by weight of a sufficiently driedpolybutylene terephthalate (PBT) (KS203F, made by Kuraray) and 20 partsby weight of the modified hydrogenated block copolymer (G-2), modifiedstyrene-based hydrogenated block copolymer (G-4) or unmodifiedhydrogenated block copolymer (R-2). The obtained mixtures were meltblended in the same manner as in Example 1 and evaluation was made inthe same manner. The results are also shown in Table 3.

As is apparent from Table 3, that in this test also compositionaccording to the present invention had better rigidity, oil resistanceand shock resistance compared with Comparative Examples 5 through 7,thus proving the marked improvement achieved by addition of the modifiedhydrogenated block copolymer.

Example 3

There were premixed 70 parts by weight of a dried PBT (KS203F, made byKuraray), 20 parts by weight of a PP (NOBLENE MA-3, made by MitsubishiPetrochemical Co., Ltd.) and 10 parts by weight of the modifiedhydrogenated block copolymer (G-2). The obtained mixture was meltblended in the same manner as in Example 1 and evaluation was made inthe same manner. The results are also shown in Table 3.

The shaped article obtained from the melt blend showed an Izod impactstrength at 25° C. of 16 kg.cm/cm, thus having improved the shockresistance to a large extent compared to PBT alone, while maintainingrigidity and oil resistance at good levels.

Example 4

Melt blending was conducted with 80 parts by weight of a commerciallyavailable polyurethane (KURAMIRON 9190, made by Kuraray Co., Ltd.) and20 parts by weight of the modified hydrogenated block copolymer (M-3) inthe same manner as in Example 1 and injection molded specimens wereobtained in the same manner.

The specimens show a retention of tensile strength after being immersedin hot water at 100° C. for 3 days of 78%, which was a markedimprovement over 62% with the polyurethane alone.

Obviously, numerous modifications and variations of the invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described herein.

                                      TABLE 3                                     __________________________________________________________________________             Example                                                                            Example                                                                            Example                                                                            Comp.                                                                             Comp                                                                              Comp.                                                                             Comp.                                                                             Comp.                                                                             Comp.                                                                             Comp.                                  1    2    3    Ex. 1                                                                             Ex. 2                                                                             Ex. 3                                                                             Ex. 4                                                                             Ex. 5                                                                             Ex. 6                                                                             Ex. 7                         __________________________________________________________________________    Formulattion                                                                  (wt. ratio)                                                                   PA66     80   --   --   100 80  80  80  --  --  --                            PBT      --   80   70   --  --  --  --  100 80  80                            PP       --   --   20   --  --  --  --  --  --  --                            M-1      20   --   --   --  --  --  --  --  --  --                            R-1      --   --   --   --  20  --  --  --  --  --                            G-2      --   20   10   --  --  --  --  --  --  --                            R-2      --   --   --   --  --  --  --  --  20  --                            M-4      --   --   --   --  --  20  --  --  --  --                            M-5      --   --   --   --  --  --  20  --  --  --                            G-4      --   --   --   --  --  --  --  --  --  20                            Properties of                                                                 shaped article                                                                Rigidity 16,800                                                                             15,000                                                                             20,000                                                                             25,600                                                                            16,800                                                                            16,000                                                                            16,200                                                                            22,000                                                                            14,500                                                                            14,700                        (kg/cm.sup.2)                                                                 Shock resistance                                                              (kg · cm/cm)                                                          25° C.                                                                         35   42   16   4.8 4.8 34  34  3.4 3.4 40                            -25° C.                                                                         35   38   --   4.0 --  6.0 10  3.0 --  3.5                           Oil resistance                                                                         good good good good                                                                              good                                                                              poor                                                                              good                                                                              good                                                                              good                                                                              poor                          __________________________________________________________________________     1 Rigidity: Bending modulus;                                                  2 Shock resistance: Notched Izod impact strength                              3 Oil resistance: Pulverized specimen was immersed in toluene for 24 hour     and measured for weight reduction.                                            good: no weight reduction;                                                    poor: some weight reduction                                              

What is claimed is:
 1. A thermoplastic polymer composition comprisingathermoplastic polymer (a) having polarity on the main chain of themolecule thereof selected from the group consisting of a polyester and apolyurethane, and a modified block copolymer (b) of a block copolymerconsisting essentially of units of the structure (B-I)n, (B-I)n-B,[B-(I/B)]n, [B-(I/B)]n-B, wherein n is an integer of 1 to 5, (B-I)-X or[B-(I/B)]-X, wherein X is a 3- to 10-multifunctional coupling agentresidue, wherein B represents a polybutadiene block having a degree ofvinylization and a degree of unsaturation of not more than 30%, Irepresents an isoprene block having a degree of vinylization and adegree of unsaturation of not more than 30%, and I/B represents apolymer block obtained by polymerizing a mixture of isoprene andbutadiene in a ratio by weight of isoprene/butadiene of 30/70 to 100/0and hydrogenating the formed polymer block in such a manner that theresulting degree of vinylization and degree of unsaturation is not morethan 30%, said block copolymer having been subjected to additionreaction with a molecular unit containing a carboxyl acid group orderivative thereof, the ratio by weight between said component (a) andsaid component (b), (a)/(b), being in the range of 2/98 to 98/2.
 2. Thethermoplastic polymer composition according to claim 1, wherein theratio by weight between said block B and said block I or I/B in saidmodified block copolymer (b) is in the range of 10/90 to 90/10.
 3. Thethermoplastic polymer composition according to claim 2, wherein theratio by weight between said block B and said block I or I/B in saidmodified block copolymer (b) is in the range of 20/80 to 85/15.
 4. Thethermoplastic polymer composition according to claim 1, wherein saidmodified block copolymer (b) has a molecular weight of 20,00 to 500,000.5. The thermoplastic polymer composition according to claim 1, whereinsaid block copolymer (b) has an amount of addition of said carboxylicacid or derivative of 0.01 to 20 parts by weight based on 100 parts byweight of said block copolymer (b) before the addition.
 6. Thethermoplastic polymer composition according to claim 1, wherein saidthermoplastic polymer (a) having polarity on the main chain of themolecule thereof is a thermoplastic polyester.
 7. The thermoplasticpolymer composition according to claim 1, wherein said thermoplasticpolymer (a) having polarity on the main chain of the molecule thereof isa thermoplastic polyurethane.
 8. The thermoplastic polymer compositionaccording to claim 1, wherein the ratio by weight between saidthermoplastic polymer (a) and said modified block copolymer (b) is inthe range of 10/90 to 90/10.
 9. The thermoplastic polymer compositionaccording to claim 8, wherein the ratio by weight between saidthermoplastic polymer (a) and said modified block copolymer (b) is inthe range of 20/80 to 85/15.